Talk:Kyanite

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Variable Hardness

This gem is difficult to facet because of the variable hardness. 7 across the width of the crystal and 5 along the length,(Webster). We can write about this in the text of the article. Therefore, at present; I am omitting the hardness in the template box until we can have some further discussion about what to do. The cleavage is perfect, and in two directions, easily developed too. More difficulty in cutting is due to fracture planes caused by multiple twinning. The fractures are seen as inclusions in all faceted kyanites according to the Larousse Encyclopedia which I frequently cite here. Tom Goodwin, G.G. 14:39, 6 February 2007 (PST)

  • Barbra has a section on her 4.37 carat emerald-cut kyanite over on the forum and it is fracture free. In light of this, it appears that we have found an error in the Larousse Encyclopedia regarding their statement of fractures seen as inclusions in ALL faceted kyanites. Because of this, I am going to have to fact-check ALL of the Larousse information that I use here.Tom Goodwin, G.G. 14:34, 9 February 2007 (PST)
Almost all cut gems are fracture free. That doesn't mean they don't fracture when you apply force on them. Maybe there is some confusion between fracture and parting. --Doos 09:27, 10 February 2007 (PST)
There IS confusion. For instance, "false" parting in corundum. In my view, "parting" is confused also with "cleavage." Tom Goodwin, G.G.
Indeed a very usual confusion. Maybe Larousse meant that all rough kyanite is fractured, not the cut. --Doos 13:51, 10 February 2007 (PST)
Barbra has carefully examined her kyanite and it is like she said, fracture-free. She posted some microphotographs of it on the forum and is trying to identify other inclusions. If kyanite is SUPPOSED to be always fractured after faceting, she has possession of the rare exception to the rule, as per Larousse. Tom Goodwin, G.G. 23:45, 13 February 2007 (PST)

Polymorphic

Kyanite is a polymorph with andalusite and fibrolite. Perhaps this will be useful when the introduction is written. Tom Goodwin, G.G. 16:01, 6 February 2007 (PST)

Yes of course it should be included (although maybe sillimanite is a more gemmo name for fibrolite). --Doos 13:53, 10 February 2007 (PST)
Agreed. sillimanite is a better name, gemologically. Tom Goodwin, G.G. 23:49, 13 February 2007 (PST)
For the project it might be best to cross reference to each other as both might be an option in a search. --Doos 10:08, 14 February 2007 (PST)
  • Very good. A cross reference will work well. Tom Goodwin, G.G. 13:17, 14 February 2007 (PST)

kyanite photograph

I don't know about anyone else, but this photo shows up with poor resolution on my monitor. There is an apparent lack of contrast with the dark background. Otherwise the stone looks very nice. Tom Goodwin, G.G. 18:47, 14 February 2007 (PST)